Change type of iconbuttons to flat type for after effect cc 2017 extend scritp

Hi, I use iconbutton on my script but in cc 2017 iconbuttons have a circle shape Around like this.

nButton = win.add('iconbutton', [0,0,20,20] ,pathFile("Files/Icons/icon.png"), { style: 'button'});

my iconbutton in cc 2017

and it in 2015

How can I remove this shape and have a normal flat button like cc 2015?

Thanks